Analysis of information sources in references of the Wikipedia article "پیشینه زبان فارسی" in Persian language version.
The continuance of Persian as the language of administration.
We see such acquaintance clearly within the Sikh court of Maharaja Ranjit Singh, for example, the principal language of which was Persian.
(...) Persian, the language originally spoken in the province of Fārs, which is descended from Old Persian, the language of the Achaemenid empire (6th–4th centuries B.C.E.), and Middle Persian, the language of the Sasanian empire (3rd–7th centuries C.E.).